Worldwide demand for front and four wheel drive vehicles has created an increasing demand for constant velocity universal joints. The Rzeppa joint, used almost exclusively at the outer ends of front axles, is exemplary of this type of joint.
Named for its inventor, A. H. Rzeppa, it consists of an outer race member, an inner race member, a ball cage and generally six driving balls. The mating surfaces between the members are spherical in shape and close fitting to one another. The driving balls fit into corresponding half grooves of the inner and outer races, the grooves having meridian lines of a sphere as their centerlines. The construction and function of the Rzeppa joint are more fully disclosed in U.S. Pat. Nos. 1,916,442 and 1,975,758.
Heretofore, the manufacture of Rzeppa and similar type joints has required large numbers of specialized machines for spherical turning, milling and grinding of the races and ball grooves. Consequently, large investments have been required which were recovered as part of the purchase price of the universal joint. Also, separate and specialized machines for each of the machining operations has made difficult the maintenance of precision tolerances.
One object of the present invention is to advance the art of metal cutting, particularly the manufacture of Rzeppa and similar type universal joints.
Another object is to provide method for manufacturing universal joints wherein machining operations for close fitting races and mating and corresponding surfaces of joint components are performed on the same machines without removing the workpieces and held in common workheads.
Another object is to provide method for manufacturing universal joints wherein relative movements between the workpieces and cutting tools, during the spherical machining of races and ball grooves, are referenced to common axes thereby duplicating the relationships between the workpieces during actual use.
Another object is to reduce the investment costs for manufacturing universal joints.
Another object is to provide method which are adaptable to the automated machining of universal joints.
The foregoing objects, along with additional objects, features, advantages and benefits of the invention become more apparent in the ensuing description and accompanying drawings which disclose the invention in detail. A preferred embodiment is disclosed in accordance with the best mode contemplated in carrying out the invention. The subject matter in which an exclusive property is claimed is set forth in each of the numbered claims at the conclusion of the description.